Several factors can cause brain-related birth defects, including genetics and environmental exposures.

Rates of birth defects affecting the brain, heart and central nervous system were higher than the state average in areas of southeastern North Carolina from 2003 to 2014, the state Department of Health and Human Services announced today. The affected counties are Bladen, Brunswick, Cumberland and New Hanover, where GenX and other per- and poly- fluorinated compounds (PFAS) have been detected in drinking water.

However, DHHS said the study results can’t establish a link between the anomalies and PFAS. The number of cases was small and varied from year to year.

According to a DHHS report, the prevalence of brain reduction defects was higher in Bladen, Brunswick and Cumberland counties. While microcephaly — an abnormally small brain — and hydrocephaly — an accumulation of spinal fluid around the brain — were more prevalent in New Hanover County. The higher prevalence of these birth defects, which included some related to heart development, was not confined to the lower Cape Fear region, DHHS said.

The prevalence of total brain defects varied substantially across the state, DHHS said. They can be caused by genetic, environmental exposure or even unknown factors.

There were 3,702 reported cases of all types of brain defects in North Carolina between 2003 and 2014. Bladen County reported 20; Pender, 32; Brunswick, 60; New Hanover, 130; and 220 Cumberland. When adjusted for population, these numbers were higher than the state average.

There are no national figures available to compare North Carolina’s rates with the rest of the US. Nor was data available for babies born at federal or military facilities, such as Womack Army Medical Center in Cumberland County. Infants born at military facilities are only included if transferred to a non-military hospital for care.

DHHS chose to analyze birth defects data because some animal studies have reported weak associations between PFAS exposure and birth defects; however, DHHS said these studies have important limitations. Animal studies, particularly using rodents, don’t necessarily reflect outcomes in humans.